There isn't a cisco cable to do this.
Have a look at black box for an RJ-21 cable / telco cable. i've found the most economical way is to buy the twin ended male and cut it in half and you then have two cables and just terminate the ends onto whatever you like. A patch panel is usually best if you have a structured cabling scheme.
here are the black box part no.s and $prices
Male 50-Pin Telco to Male 50-Pin Telco
5-ft. (1.5-m)
ELN27T-0005-MM
67.95
25-ft. (7.6-m)
ELN27T-0025-MM
103.95
50-ft. (15.2-m)
ELN27T-0050-MM
142.95
100-ft. (30.4-m)
ELN27T-0100-MM
217.95
Paul
